Cause of Delirium

Which one of the following is the most likely cause of a new delirium in a cancer patient:

a. adverse drug effect
b. alcohol withdrawal
c. brain metastases
d. hyponatremia

Answer a.

All of the options can cause delirium, but by far, adverse drug effects are the most common. Many of the drugs used to treat other symptoms have delirium as a toxicity: anti- cholinergics, anti-depressants, anti-emetics, benzodiazepines, opioids, etc. In one study, cancer patients exposed to daily doses equivalent to lorazepam above 2 mg, above 15 mg of dexamethasone (or its equivalent) or above 90 mg of subcutaneous morphine (or equivalent) were at the highest risk for developing delirium. Delirium in palliative care settings is frequently multifactorial with more than one etiology involved.Of note, in cancer patients, brain metastases is often first on clinicians minds when confronted with new onset delirium; in fact, most patients present with a focal finding such as aphasia or hemiparesis, rather than delirium, a more global sign of brain dysfunction. Don’t forget other causes of delirium, especially in the elderly, such as new infection, urinary retention or constipation.

For further reading and evidence, see:

  1. Incidence, etiology and reversibility of delirium:
  2. Psychoactive Medications and Risk of Delirium in Hospitalized Cancer Patients:
  3. Evidence-based summary (2014):

See Fast Fact #1 Terminal Delirium